Background: Knee osteoarthritis (KOA), is a chronic de-generative joint pathology with a global prevalence of 22.9% in individuals aged 40 and over. It is a leading cause of disability and poor quality of life worldwide due to musculoskeletal pain and functional limitations. Aim of Study: This study aimed to investigate and identify the clinical prediction rules for the severity of functional disa-bility in KOA. Subjects and Methods: Eighty patients between 50-65 years old suffering from KOA from both genders were recruit-ed for this study. Every patient was assessed by the visual an-alogue scale (VAS) to measure pain intensity and the Western Ontario and McMaster University Arthritis Index (WOMAC) Arabic version to assess knee functional disability. Results: Multivariate analysis revealed that the most sig-nificant predictors of severity of functional disability in knee osteoarthritis were pain intensity followed by functional disa-bility, with p-value (p<0.05). Conclusion: Pain intensity, functional disability are signif-icant predictors of KOA progression. These factors should be closely monitored and targeted in clinical practice to effectively manage and potentially slow the progression of knee osteoar-thritis.